1. Field of the Invention
The present invention relates generally to lawn maintenance equipment, particularly to turf treatment devices of the type adapted to be connected to a powered vehicle, such as a tractor, truck, utility vehicle, lawn mower, and the like for towing over the ground or turf to be treated, for aerating, rolling, slicing, and seeding the soil of a lawn to cultivate thick and healthy grass.
2. Description of the Related Art
Modern lawns and grass fields require a great deal of care and attention in order to nurture a thick green carpet of grass. Such care includes consistent mowing, watering, and thatching as well as periodic overseeding and fertilization. In addition, it is imperative that a healthy lawn be aerated at least twice a year and, preferably, even more often. The importance of aerating lawns to permit water, oxygen, and nutrients to reach the grass root region has been recognized for sometime by experts in lawn care, particularly those involved in maintaining functional lawn areas such as golf courses, athletic fields, parks, and other suitable grassy areas. Aeration usually entails creating a multitude of closely spaced small holes in the surface of the ground to permit air and oxygen to be absorbed into the soil. The holes also tend to increase moisture penetration into the soil and serve as receptacles for grass seed to prevent the seed from being washed away and to promote germination and growth. Thus, aeration of turf in particular is essential to allow ventilation to accelerate decomposition of thatch and humus and to provide solid access for nutrient supply and for reseeding.
Numerous turf treating devices have been previously proposed. For example, drums have been used to roll or compact the ground. Further, devices having a large cylindrical drum studded about its periphery with a plurality of short radially extending spike-cores have been used to be rolled or pulled over the ground such that when it rolls, the spike-cores are driven into the soil to remove plugs or cores of soil and/or grass thereby creating shallow holes. Similar devices involve a roller or rotatably mounted element equipped with soil penetrating elements, which usually comprise disc-like knives, spoon tines or hollow coring tines.
For example, in U.S. Pat. No. 5,823,269 there is disclosed a turf aerator attachment for a tractor comprising a frame and a plurality of aerator disc assemblies. Each aerator disc assembly comprises a plurality of aerator disc mounting arms extending between the frame and the aerator disc axle. The mounting arms are rotatably journalled on the frame to thereby permit pivotable movement of each of the aerator disc assemblies. Interconnecting means are utilized to interconnect aerator disc assemblies. The arrangement allows for the turning of the aerator apparatus without damage to the equipment and turf.
In U.S. Pat. No. 5,579,847 there is disclosed a compact lawn aerator comprising a rigid frame having a hitch for releasibly fastening the frame to the back of a self-propelled mower. An elongated axle is secured to the under side of the frame and a set of aerator wheels are rotatably mounted at spaced intervals along the axle. Each of the aerator wheels has a generally disc-shaped hub from the periphery of which four spikes radiate. Each spike initially projects from the hub along a radius but curves along its length in the direction of rotation of the wheel. The spikes are tapered to a sharpened point and their curve is determined so that, as the wheel rotates, the ends of the spikes pierce the soil at substantially right angles and the shank of the spikes slip into the ground progressively through the pierce point. This greatly reduces the force needed to drive the spikes into the ground, thus reducing the weight and size of the device.
In U.S. Pat. No. 4,776,404 there is disclosed an implement for aerating and dethatching turf having multiple aerator units each including a plurality of earth piercing aerator elements mounted on a shaft. Arms of each aerator unit supporting the shafts are independently swingable to move the shafts between horizontal positions and positions inclined from horizontal in accordance with the contour of the ground or encountered soil conditions as the aerator is advanced across the earth. A spring assembly urging each aerator unit toward the ground has structure for causing any upward swinging movement of the arms of each unit to be resisted by the weight of the frame whenever such arms are pivoted upwardly passed a predetermined elevation, in order to provide additional force where highly compacted soil conditions are found. Springs common to adjacent aerator units engage a bracket that is shiftably connected to adjacent arms of the unit to enable the common spring to direct its extension force on the arm which is in the higher position.
However, the foregoing turf perforating or treating machines do not provide for a retraction structure or the like which is selectively and momentarily operable to move the perforating, rolling, or turf treating device to a non-performing position, thus enabling the machine to be moved across areas which would be damaged by the turf treatment tools or where turf treatment operations are not desired. For example, golf courses typically have cart paths, stone or plate yardage markers, underground watering systems which provide for periodic key-hole access structure, water head piping, or automated spray disc discharge of water, and other special lawn areas or structure wherein it is desirable to selectively and momentarily disengage turf treatment operations before resuming the same. Other lawns may have exposed root structure, stones or other impenetrable hard objects, field boundary markers or other conditions where is also desirable to selectively and momentarily disengage turf treatment operations before resuming the same.
Several attempt have been made to address this problem. For example in U.S. Pat. No. 4,867,244 there is disclosed a walk-behind turf aerating apparatus which includes two pairs of tine arm assemblies, each assembly having a pair of vertically reciprocating tine arms for driving coring tines into the turf. A tine arm return mechanism includes a gear box for each pair of tine arms, the lower ends of the tine arms being connected to cranks extending from the gear box to reposition the tine arms prior to ground engagement. Stops are provided to limit the tine arm travel. A spring-loaded lifting mechanism permits manual shifting of the tine arm mechanism form a lowered ground-engaging position to a raised transport position. A belt drive with clutch and reduction drive for the wheels also drives the tine arm mechanism with automatic disengagement when the wheels are in the transport position. A handle assembly is connected to the apparatus frame through a pivotal connection including vibration damping elements for minimizing transmittal of vibrations, particularly in the vertical plane, to the handle.
In U.S. Pat. No. 4,158,391 there is disclosed a soil aerating device which is adapted for connection to a powered vehicle which includes a first frame rotatably supporting a drum carrying a plurality of core-forming tines adapted to penetrate the ground or turf to be aerated and remove a plug of soil and/or grass as the drum is rolled over the surface of the ground or turf, and which further includes a second frame having a forward and rear portions. The first frame is pivotally connected to the rear portion of the second frame for limited relative pivotal movement between the two frames and the forward portion of the second frame is pivotally connected to the vehicle for pivotal movement of the two frames relative to the vehicle between a raised position wherein the drum and tines are disengage from the ground or turf and a lowered position wherein the drum is in engagement with the ground or turf. An actuator, such as a double-acting, hydraulically-actuated ram, connected between the vehicle and a second frame moves the two frames between the raised and lowered positions and applies a downward force on the second frame, when the two frames are in the lowered position, to thereby transfer a portion of the weight of the vehicle to the drum through the second frame, the pivotal connection between the first and second frames, and the first frame. The pivotal connection between the two frames permits the first frame and the drum to pivot relative to the second frame, thereby assuring full penetration of the tines as the drum rolls over hills and down into valleys in the ground or turf with a minimal effect on the ground-engaging traction of the vehicle wheels.
In U.S. Pat. No. 4,084,642 there is disclosed a turf perforating machine for aerating lawns by removing plugs therefrom comprising a wheeled frame having a plurality of reciprocating tools, each connected by a linkage to an eccentric mounted on a journal and each linkage slidably mounted in a pivotal guide secured to the journal which prevents binding of the linkage as a frame is moved across the lawn and the tool is disposed in the ground, and further including a retractor unit for pivoting the guide, linkage and tools to a nonperforming position.